ABSTRACT Temperature and nutrition are two prominent environmental variables influencing insect life from development to reproduction. Here, we assessed various components of fitness (developmental times, survival rates, egg production, and weight gain) of Tribolium confusum fed on wheat, barley or corn flour at 15, 27 and 35°C with a view of understanding its level of susceptibility. The shortest developmental times, the highest survival percentage, egg production, and weight gain were achieved by feeding larvae on wheat flour at 35°C, while the opposite results were attained by feeding larvae on barley or corn flour at 15°C. Interaction of temperature × diet significantly affected the above-mentioned biological features. The correlation between the alterations in the biological features and the main nutrients of the flours tested (total protein, carbohydrate, and lipid contents) is discussed. The results of this study suggest the value of a strategy for managing T. confusum by exposure to low temperatures.